With a number of hazardous industrial and other processes, it is necessary to protect the face and eyes of a worker by some protective panel in front of the face. Such a panel may consist of a transparent visor which has sufficient strength to resist the impact of dangerous substances or objects such as hot or cold splinters of metal.
With the exception perhaps of suitably toughened glass, there is no known and economically viable transparent material which will withstand for very long, the impact of the substances or objects from which the wearer of a protective visor is to be protected. Thermoplastic materials such as, say, polycarbonate in sheet form are commonly used for transparent protective visors and the outer surface can rapidly become damaged by the impact of the aforesaid substances or objects. Additionally the surface may become scratched if used in generally dusty environments, especially where the dust is of an abrasive nature. The damage to the visor seriously reduces the necessary optical clarity and the visor has to be replaced to avoid consequent inconvenience and perhaps danger to the user, arising from the reduced visibility and the visual flaring which can occur when light impinges on scratches etc., on the visor surface. Visor replacement costs can thus be high, due to the short life of the visor material and inconvenience is also caused by the requirement for frequent replacement.
It is known art to reduce this visor problem by using a replaceable visor of minimum size contained in an aperture with a shield or frame of larger size. The shield or frame may have a longer life expectancy than the transparent visor panel, thus reducing replacement costs. This application is concerned with an improved design of frame and with improved means of securing the visor panel in the frame to permit easy and quick replacement of the visor panel.
Existing visor frames tend to divide into two categories. One category consists of an opaque shield with a relatively small aperture for a visor panel. This type is commonly used for welding operations. The second category consists generally of a very narrow frame intended to hold a visor panel of large area to provide a large angle of vision. Such narrow frames tend to be flexible and non-sturdy and prone to damage, especially when the visor panel is not in position in the frame.